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The Active Database Management System

The Active Database Management System. PDT 2008 Genci. Zdroje. [1] Dittrich et al.:The Active Database Management System Manifesto: A Rulebase of ADBMS Features. Proc. 2nd Workshop on Rules in Databases (RIDS), Athens, Greece, September 1995. LNCS, Springer 1995

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The Active Database Management System

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  1. The Active Database Management System PDT 2008 Genci

  2. Zdroje [1] Dittrich et al.:The Active Database Management System Manifesto: A Rulebase of ADBMS Features.Proc. 2nd Workshop onRules in Databases (RIDS), Athens,Greece, September 1995. LNCS, Springer 1995 [2] Paton N., Diaz O.: Active Database Systems.ACM Computing Surveys, Vol. 31, No. 1, March 1999 [3] Carlo Zaniolo a kol.: Advanced Database Systems, Morgan Kaufman Publishers, San Francisco, 1997 (kapitoly 2-3). Mnohé veci nájdete v prezentáciách študentov prof. Pokorného na stránke: http://www.ksi.mff.cuni.cz/~pokorny/dj/

  3. What the term “active database management system” means: • being able to react automatically to situations in the database and beyond • allowing the specification and implementation of reactive behavior • ADBMSs extend “passive” DBMS with the possibility to specify reactive behavior

  4. ECA-rules • Event-condition-action rules • When an event occurs, check the condition and if itholds, execute the action

  5. Event • An event is something that happens ata point in time. • Possible alternatives: • structure operation (insert, update, access); • behavior invocation (the message display is sent to an object of type widget); • transaction (abort, commit, begin-transaction); • abstract or user-defined(response tosome information entered by a user); • exception (an attempt to access some data without appropriateauthorization); • clock (the first day of everymonth); • External(the temperature readinggoes above 30 degrees)

  6. Event Granularity • indicates whether an event is defined: • for every object in a set (e.g., every instance of a class), • for given subsets (e.g., all staff members except professors) • for specific members of the set (e.g., to prevent unauthorized access to specific instances)

  7. Type of an event • Primitive - in which case the event is raised by a single low-level occurrence that belongs to one of the categories described • Composite - in which case the event is raised by some combination of primitive or composite events using a range of operators that constitute the event algebra

  8. Condition • The condition indicates whether it must be given. • In ECA-rules, the condition is generally optional.

  9. Action • The range of tasks that can be performed • Actions may: • update the structure of the database or rule set, • perform some behavior invocation within the database or an external call, • inform the user or system administrator of some situation, • abort a transaction, • take some alternative course of action using do-instead

  10. Characteristics of ADBMSs • Essential Features • An ADBMS is a DBMS • An ADBMS supports definition and management of ECA-rules • An ADBMS has to provide means for defining events, conditions, and actions • An ADBMS must support rule management and rulebase evolution

  11. Characteristics of ADBMSs (2) • An ADBMS has an execution model • An ADBMS must detect event occurrences (situations) • An ADBMS must be able to evaluate conditions • An ADBMS must be able to execute actions • An ADBMS has well-defined execution semantics • Conflict resolution must either be pre-defined or user-definable

  12. Characteristics of ADBMSs (3) • Optional Features • An ADBMS should represent information on ECA-rules in terms of its data model • An ADBMS should support a programming environment • An ADBMS should be tunable

  13. Realita • Active rules = triggery • Sú implementované vo väčšine DBMS • Experimentálne systémy: • Starburst • Chimera

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